In the first of two experiments, men read news articles that described the local population as having either more men or more women. Then they were asked about spending and saving habits in that scenario. In the case in which women were scarcer, men said they’d save 42% less per month and borrow 84% more.

Separately, men were shown photograph sequences with differing ratios of men and women in the pictures. Then they were asked to choose between taking $20 now or $30 in a month. Again, in the cases where women were scarce in the photos, men opted for the money now.

The hypothesis here is that decisions aren’t made on a conscious level. The men were not made aware of the scarcity of women and the mere sight of more men subconsciously made them impulsive, competitive and flipped the urge to spend more now. In the real world, the same proved to be true. After examining the sex ratios of 120 U.S. cities, researchers found that single men have more credit cards and higher debt levels in cities where the sex ratios indicate fewer women.

Conversely, women’s spending ratios didn’t change, but they did overwhelmingly agree that men should spend more on their dates and Valentine’s gifts when they’re in the majority.